Binding and Transport of Benzo[a]pyrene by Blood Plasma Lipoproteins: The Possible Role of Apolipoprotein B in This Process

Citations Over Time

Abstract

The role of plasma lipoproteins as carriers in the transport of benzo[a]pyrene was assessed in in vitro and in vivo studies. Addition of [3H]benzo[a]pyrene to rat plasma resulted in binding of the xenobiotic to lipoproteins. Studies of labeled benzo[a]pyrene distribution in rat blood plasma by the method of ultracentrifugation have given the following results: high-density lipoproteins, 40%; low-density lipoproteins, 14%; very-low-density lipoproteins, 23%; other plasma proteins, 23%. Complexes of benzo[a]pyrene-lipoproteins were isolated by gel filtration with Sephadex G-25 and used for intravenous injection in rats. Biodistribution studies have shown different localization of benzo[a]pyrene in rat organs and tissues depending on lipoprotein classes. A high amount or radioactivity was bound by the liver and adrenals when all classes of lipoproteins were used, but especially with high-density lipoproteins. High levels of benzo[a]pyrene were measured in the kidneys. Equilibrium dissociation constants for complexes of benzo[a]pyrene with high-density lipoproteins and low-density lipoproteins were obtained (Kd 4.1 x 10(-5) and 1.5 x 10(-5) M, respectively). Binding and distribution of the protein component of lipoproteins were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. More than 80% of the radioactivity recovered from the gel was localized in the area of apolipoprotein B. After isolation and purification of apolipoprotein B, the equilibrium dissociation constant for complexes of benzo[a]pyrene with apolipoprotein B was obtained, and its value indicated that apolipoprotein B might be the main protein carrier for benzo[a]pyrene.

Related Papers

• → An ultracentrifugal study of the self-association of canine apolipoprotein A-I in solution(1977)7 cited
• → Purification and properties of 6-phosphogluconate dehydrogenase from sheep liver(1969)37 cited
• → Sedimentation equilibrium in the analytical ultracentrifuge(2000)9 cited
• → Determination of the molecular weight of detergent-solubilized enzymes by sedimentation equilibrium in an air-driven ultracentrifuge(1982)8 cited
• Routine titration of foot-and-mouth disease virus suspensions by analytical ultracentrifugation 2nd communication: sedimentation equilibrium method.(1977)